JP2008101115A - Refrigerating agent and refrigerating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating agent which is used for keeping cool an article to be cooled that has a suitable cooling temperature in the range of >0°C and <10°C and which satisfies the following characteristics: (1) having no or a little fluidity; (2) having a phase change temperature (melting point) in response to a suitable temperature or temperature range (henceforth "suitable cooling temperature") desired for an article to be kept cool (henceforth "keeping cool article"); (3) having a large latent heat; (4) having a large specific heat in the liquid state of the refrigerating agent; (5) repeated solidifications and thaws do not cause the phase separation or the deterioration of the properties; (6) the change of the thawing temperature is as small as possible; and (7) being inflammable, and to provide a refrigerating material comprising the refrigerating agent and a case or a bag holding the refrigeration agent therein. <P>SOLUTION: The refrigerating agent comprises a tri-n-butyl alkyl ammonium salt, water and a gelling agent. Alternatively, it comprises brominated tri-n-butyl n-pentyl ammonium, water and a gelling agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a cold insulation agent used for storage, transportation, cooling and the like at low temperatures in the fields of foodstuffs, processed food products, medicine, and the like, and a cold insulation material filled with the cold insulation agent in a container.
In the present invention, a substance having a cold-retaining (or cooling) function is referred to as a “cold-retaining agent”, and a substance that is filled in a container, a bag, or the like and used for cold-retention is referred to as a “cold-retaining material”.

Fresh fish and shellfish, fresh vegetables, fruits, meat, other fresh foods, processed foods, dairy products, flowers, films, medicines, medical specimens etc. are transported under low temperature control or temporarily in a place without cold storage facilities In order to maintain these freshness, taste, quality, performance, and utility when stored at a low temperature, a cold insulating material is used.
The cold insulator is also used for cooling such as local cooling of the human body.

  Various compositions that utilize latent heat associated with phase change have been employed as a cryogen. Since the latent heat cooling agent that has been cooled and solidified in advance has latent heat, it is melted at a certain melting temperature, so that the object to be cooled can be kept at a low temperature.

The following are listed as properties required for the refrigerant.
(1) No melting or small fluidity when melted When the container or bag body is filled with a cooling agent and used as a cooling material, it will flow out and adhere to the object to be cooled even if the container or bag body is damaged. In order to avoid contamination or contamination, it is preferable that there is no fluidity during melting or that it is small, that is, it is gelled or solidified.
(2) A phase change temperature (melting point) corresponding to an appropriate temperature or temperature range (hereinafter referred to as “appropriate cooling temperature”) desired for an article to be kept cold (hereinafter referred to as “cooled object”). It is desirable that the melting temperature (corresponding to the melting point) or the melting temperature range that is maintained until the latent heat that has been melted and stored is released corresponds to the appropriate cooling temperature of the object to be cooled.
(3) Large amount of latent heat If the amount of latent heat is large, it takes a long time for the solidified cryogen to melt and release the stored latent heat, and the time for maintaining the melting temperature is long. This is preferable because it takes a long time.

(4) The specific heat in the melted state of the cryogen is large. After the solidified cryogen is melted and the release of latent heat is finished, the temperature of the melted cryogen increases, but the specific heat in the melted state of the cryogen is large. And it takes a long time for the temperature of the cryogen to reach the ambient temperature, and the object to be cooled can be held for a long time at a temperature closer to the appropriate cooling temperature, and the freshness, quality, performance, utility, etc. of the object to be cooled Can be delayed.
(5) Phase separation does not occur due to repeated solidification and melting, and performance does not deteriorate. The cryogen is required to have the property of withstanding repeated use of solidification and melting. Therefore, it is necessary that the phase separation phenomenon that does not partially melt at the time of melting and remain as a solid phase or the heat storage performance deteriorate due to repeated solidification and melting that repeatedly accumulate and release latent heat.
If necessary, (1) no or small fluidity, (2) melting point corresponding to the appropriate cooling temperature, (3) large latent heat, (4) large specific heat in the molten state, (5) repeated It can be said that being able to withstand use is an important property that the latent heat cryogen used as the cryogen should have.

(6) When the latent heat cryogen that has been cooled and solidified in advance melts, the melting temperature does not change with the progress of melting, or the melting temperature changes as little as possible. More preferably, the object to be cooled can be kept at a constant temperature and a low temperature.
Furthermore, (7) nonflammability is also required.

Further, in the field of air conditioning, there are materials that mainly use ice, paraffin, inorganic hydrates, organic hydrates, etc. as regenerators using latent heat, and it is conceivable to use these as latent heat coolers.
Trimethylolethane (TME) hydrate is known as a latent heat regenerator mainly composed of organic hydrates, and studies are being made centering on TME-water-urea ternary systems (patents). Reference 1).
Moreover, there exists a hydrate of a quaternary ammonium compound as another example of the latent heat cool storage agent which uses an organic hydrate as a main ingredient (refer patent document 2).
JP 2000-256659 A Japanese Patent No. 3641362

  Many of the objects to be kept cool mainly for food such as fresh fish, fresh food, and dairy products have an appropriate cooling temperature in the range of 0 to 10 ° C. As described above, the latent heat regenerator having a melting point in this temperature range includes, for example, ice, paraffin, inorganic hydrate, organic hydrate and the like as a main ingredient.

  Ice is generally used for cold storage during the distribution of fresh fish, but since it is kept cold at 0 ° C, it has the same high commercial value as live fish and is called "living" from just after death to complete rigidity. There is a problem that it cannot be kept in the range of 5 to 10 ° C. suitable for maintaining the temperature, and cannot be used as a cryogen at a temperature higher than 0 ° C. in order to distribute “live” fresh fish with high commercial value.

  Since paraffin is flammable, it is problematic for use as a cryogen. Inorganic hydrates do not satisfy the above condition (5) that phase separation does not occur or performance deteriorates due to repeated solidification and melting, and are unsuitable as a cooling agent. For example, a cold storage agent in which ammonium chloride or the like is added as a melting point adjusting agent to sodium sulfate decahydrate is known as an inorganic salt hydrate cold storage agent having a melting point of 9 ° C. However, if solidification and melting are repeated, it tends to cause phase separation. is there.

  The heat storage material composition comprising the clathrate hydrate of Patent Document 1 as a main ingredient is said not to cause phase separation even if the solidification and melting are repeated 100 times, but the melting point is higher than 10 ° C, so 0 to 10 ° C. Therefore, it is not suitable for the cooling of “living” fresh fish that is required to be kept in the range of 5 to 10 ° C.

In addition, among the latent heat regenerators mainly composed of clathrate hydrates of quaternary ammonium compounds of Patent Document 2, tetra nbutylammonium bromide (TBAB) will be described as an example. The melting point (harmonic melting point) of the TBAB aqueous solution of about% by weight is about 12 ° C., and heat storage and heat dissipation are repeated without phase separation at this temperature. However, although the condition of the cryogen that can withstand repeated use is satisfied, it cannot be used as a cryogen for an object to be cooled having an appropriate cooling temperature in the range of 0 to 10 ° C. (The harmonic melting point will be described later.)
As described above, the latent heat coolers that have been put to practical use or proposed so far have their respective problems.

  The present invention has been made in order to solve these problems, and is used for keeping a cooled object having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C., and satisfies the above (1) to (7). An object of the present invention is to provide a cold insulation material that is configured by filling a container or a bag with the cold insulation agent.

(1) The cryogen according to the present invention is characterized by containing a tri-n-butylalkylammonium salt, water, and a gelling agent.

A gel-like product obtained by adding a gelling agent to an aqueous solution containing tri-n-butylalkylammonium salt and water is cooled to produce a tri-n-butylalkylammonium salt hydrate, and the refrigeration is mainly composed of the hydrate. It can be used as an agent. The gelling agent is added to this aqueous solution to increase the viscosity to a gel-like material, so there is no fluidity or smallness, so even if the container or bag filled with the cold insulation agent breaks, it flows out and becomes a cold object. There is no adhesion or contamination.
Examples of the alkyl include n-pentyl, isopentyl, npropyl, isopropyl, ethyl, methyl, nhexyl, isohexyl, nheptyl, isoheptyl, isobutyl and the like other than nbutyl.
As ammonium salts, ammonium bromide, ammonium chloride, ammonium fluoride, ammonium nitrate, ammonium nitrite, ammonium chlorate, ammonium perchlorate, ammonium bromate, ammonium iodate, carbonic acid Ammonium salts, ammonium phosphate salts, ammonium tungstate salts, ammonium sulfate salts, ammonium hydroxide salts, ammonium carboxylates, ammonium dicarboxylates, ammonium sulfonates, ammonium disulfonates and the like can be mentioned.

  As a gelling agent, the viscosity is increased by adding it to gel or solidify, butyric acid (butyric acid), valeric acid (valeric acid), caproic acid, enanthic acid (heptylic acid), Caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, Carboxylic acids such as octylic acid, oleic acid, ricinoleic acid, hydroxystearic acid and isostearic acid, or a compound of the carboxylic acids with any of sodium, potassium, lithium, calcium, barium, zinc, magnesium, aluminum and lead Etc.

  It is preferable to add the gelling agent to an aqueous solution containing tri-n-butylalkylammonium salt in a range of 0.1 to 10 wt% with respect to the aqueous solution. When the content is less than 0.1 wt%, gelation does not occur, and when the content is greater than 10 wt%, the heat storage amount of the cooling agent is significantly reduced. It is more preferable that the content be in the range of 0.3 to 5 wt% because gelation can be reliably achieved and the decrease in the heat storage amount of the cryogen can be ignored.

  In addition, it is presumed that the interaction between constituent molecules of the cryogen is strengthened by adding a gelling agent to form a gel-like material, so that there is an effect of improving the thermal conductivity during cooling.

Although the aqueous solution of the hydrate product is cooled and the hydrate formation temperature (melting point) is reached and the temperature is further lowered, the hydrate is not formed and the state of the aqueous solution is maintained. When this hydrate is used as a cryogen, if this supercooling is large, the temperature at which the aqueous solution is cooled must be considerably lowered, which is a problem. Therefore, it is necessary to make the supercooling as small as possible and prevent the supercooling. In order to prevent supercooling, conventionally, fine particles are mixed in an aqueous coolant solution to release supercooling as a hydrate nucleation material.
However, even if fine particles are mixed to prevent overcooling when producing hydrates, the effect of preventing overcooling will be lost if the fine particles are not uniformly dispersed, and fine particles will be generated if solidification and melting are repeated. Is separated and the effect of preventing overcooling is lost.
In this regard, by adding a gelling agent to an aqueous solution of the hydrate product to obtain a gel-like product, it is presumed that the molecular arrangement in the crystallized state is preserved to some extent. There is an effect to be canceled. Since overcooling can be prevented, the cooling temperature does not need to be excessively lowered, and energy can be saved.

(2) Further, it is characterized by containing tri-n-butyl-n-pentylammonium bromide, water and a gelling agent.

(3) Further, tri-n-butyl-n-pentylammonium bromide hydrate is a main component and a gelling agent is included.

  Tri-n-butyl-n-pentylammonium bromide forms clathrate hydrate, the concentration giving a harmonic melting point is 34% by weight and the harmonic melting point is approximately 6 ° C. The amount of latent heat at this harmonic melting point is 193 J / g, which has a high amount of latent heat. The specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K. Further, even if solidification and melting are repeated, there is no decrease in phase separation or heat storage performance. Since it has such a characteristic, it is suitable as a main component of the cold-retaining agent for the object to be cooled having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C.

(4) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride, water and a gelling agent.

(5) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride hydrate as a main component and containing a gelling agent.

  Tri-n-butyl-n-pentylammonium chloride forms a clathrate hydrate, the concentration giving the harmonic melting point is 33% by weight, the harmonic melting point is approximately 9 ° C., and the latent heat at the harmonic melting point is 195 J / g, It has a high amount of latent heat. The specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K. Further, even if solidification and melting are repeated, there is no decrease in phase separation or heat storage performance. Since it has such a characteristic, it is suitable as a main component of the cold-retaining agent for the object to be cooled having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C.

(6) Further, it is characterized by containing a tri-n-butylalkylammonium salt, a tetraalkylammonium salt, water and a gelling agent.

  When the aqueous solution of tri-n-butylalkylammonium salt and tetraalkylammonium salt is cooled, tri-n-butylalkylammonium salt hydrate and tetraalkylammonium salt hydrate are produced. By producing two hydrates having different melting points, thermal characteristics different from those of a single hydrate can be obtained.

Examples of the alkyl in the tetraalkylammonium salt include n-butyl, isobutyl, npentyl, isopentyl, npropyl, isopropyl, ethyl, methyl, nhexyl, isohexyl, nheptyl, isoheptyl, isobutyl and the like. As ammonium salts, ammonium bromide, ammonium chloride, ammonium fluoride, ammonium nitrate, ammonium nitrite, ammonium chlorate, ammonium perchlorate, ammonium bromate, ammonium iodate, carbonic acid Ammonium salt, ammonium phosphate salt, ammonium tungstate salt, ammonium sulfate salt, ammonium hydroxide salt, carboxylic acid ammonium salt, dicarboxylic acid ammonium salt, sulfonic acid ammonium salt, disulfonic acid ammonium salt Umm salts and the like.
Specific examples of the tetraalkylammonium salt include, for example, tetra nbutylammonium bromide.

(7) Further, it is characterized by containing tri-n-butyl-n-pentylammonium bromide, tetra-n-butylammonium bromide, water and a gelling agent.

(8) Further, it is characterized in that it contains tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate as main components and contains a gelling agent.

Produces a hydrate with a different melting point from tri-n-butyl-n-pentylammonium bromide hydrate, for example, a tetraalkylammonium salt such as tetra-n-butylammonium bromide and tri-n-butyl-n-pentylammonium bromide mixed with water By doing so, the temperature at which the hydrate is formed when the mixed aqueous solution is cooled (mixture melting point) can be made lower or higher than the melting point of tri-nbutyl n-pentylammonium bromide hydrate alone.
Therefore, the melting point of the mixture can be adjusted to a desired range by adjusting the composition of tri-n-butyl-n-pentylammonium bromide and the tetraalkylammonium salt. Therefore, it is possible to provide a cryogen having a melting temperature that matches an appropriate cooling temperature desired for the object to be cooled.
It has been confirmed that the total latent heat amount of the mixture is substantially equal to the sum of the latent heat amounts of tri-n-butyl-n-pentylammonium bromide hydrate and tetraalkylammonium salt hydrate multiplied by the blending composition ratio.

(9) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride, tetra-n-butylammonium bromide, water and a gelling agent.

(10) Further, it is characterized in that it contains tri-n-butyl-n-pentylammonium chloride hydrate and tetra-n-butylammonium bromide hydrate as main components and contains a gelling agent.

(11) The cold insulating material according to the present invention is characterized by filling a container or a bag with the cold insulating agent according to any one of the above (1) to (10).

As the container or bag body filled with the cold insulation agent, a known one used as a container or bag body of a cold insulation material can be used. For example, bags or containers (bags / packs that contain jelly drinks or shampoos for refills), plastic molding, made of a flexible material sheet made of synthetic resin film laminated with metal foil (such as aluminum foil) Examples include containers.
A cold insulation material is prepared by filling a plastic container or bag body with a cold insulation agent, and the cold insulation material is cooled in advance, and is stored in a cold insulation container together with an object to be cooled and distributed and stored.

  The cryogen of the present invention comprises a tri-n-butylalkylammonium salt, water and a gelling agent, has a melting point corresponding to an appropriate cooling temperature of 0 ° C. to 10 ° C., and has a latent heat amount. Has a characteristic that it has a large specific heat in a molten state and can withstand repeated use, and has no fluidity in the molten state, and therefore has an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C. It is suitable as a cooling agent for the object to be cooled.

As an example of the present cold-retaining agent, first, characteristics of a hydrate that is a main component will be described, and further, an example in which a gelling agent is added to a hydrate that is a main component will be described.
The characteristics of hydrate examples as the main component are shown in Table 1 below, and each hydrate example will be described based on Table 1.

1) Main component example 1: Tri-n-butyl-n-pentylammonium bromide (TBPAB) harmonic concentration hydrate DSC (Differential Scanning Calorimeter) measurement is performed on tri-n-butyl-n-pentylammonium bromide aqueous solution at different concentrations. The melting point and latent heat amount of shishi hydrate were measured. As a result, it was confirmed that the melting point became maximum at a weight concentration of 34% in the phase diagram with the melting point temperature on the vertical axis and the concentration on the horizontal axis, and the concentration giving the harmonic melting point (called the harmonic concentration) was 34%. The definition of the harmonic melting point will be described later.

The harmonic melting point was 6 ° C., the amount of latent heat was 193 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.7 J / g · K.
Thus, the latent heat amount at the harmonic melting point of tri-n-butyl-n-pentylammonium bromide hydrate is 193 J / g, and since it has a large latent heat amount, the solidified hydrate melts and releases the stored heat. It takes a long time to finish. Therefore, since the time that is maintained at the melting temperature is long, the time that is maintained at the appropriate cooling temperature is excellent when used as a cryogen.

In addition, the specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K, and since the specific heat is large, it is difficult to raise the temperature, and the time until the temperature of the aqueous solution reaches the ambient temperature becomes long. Therefore, it is preferable that the object to be cooled can be kept at a temperature close to the appropriate cooling temperature for a long time when used as a cryogen.
It was also confirmed that there was no decrease in phase separation or heat storage performance even after solidification and melting 1000 times.
Furthermore, tri-n-butyl-n-pentylammonium bromide hydrate is preferred without toxicity.

  As described above, tri-n-butyl-n-pentylammonium bromide hydrate has such characteristics. Therefore, the cold-retaining agent for the object to be cooled having an appropriate cooling temperature in the range higher than 0 ° C. and lower than 10 ° C. Suitable as a main component.

The harmonic melting point means that the composition before and after the phase change from an aqueous solution (liquid phase) to a hydrate (solid phase) does not change when an aqueous solution of a compound that forms a hydrate is cooled to produce a hydrate. The temperature of the case (eg, producing a hydrate with the same concentration as the compound concentration that produces the hydrate in the original aqueous solution). In the state diagram in which the vertical axis represents the melting point temperature and the horizontal axis represents the concentration, the maximum point is the harmonic melting point.
In the present specification, a concentration that provides a harmonic melting point is referred to as a harmonic concentration.
When an aqueous solution with a harmonic concentration is cooled, hydrates begin to form at the harmonic melting point, and the temperature is constant at this melting temperature until all aqueous solutions are hydrated. Similarly, melting occurs at this constant melting temperature. If the hydrate has a harmonic concentration, there is no change in the melting temperature at the time of melting, and the melting temperature is constant at the harmonic melting point.
When the concentration is lower or higher than the harmonic concentration, the melting temperature becomes lower than the harmonic melting point.
When an aqueous solution having a concentration lower than the harmonic concentration is cooled to melt the solidified hydrate, melting begins at a temperature lower than the harmonic melting point, and the melting temperature gradually increases as the melting proceeds.

2) Main component example 2: Tri-n-butyl-n-pentylammonium bromide (TBPAB) hydrate less than harmonic concentration For hydrates less than harmonic concentration, the melting temperature changes as the melting progresses, but the concentration By making the concentration less than the harmonic concentration, the melting temperature region can be made a region having a temperature lower than the harmonic melting point, so that the object to be kept cold can be used as a cold insulating agent that can be kept in a certain temperature region.
In the main component example 2, as shown in Table 1, a hydrate was formed by cooling, for example, an 18% aqueous solution having a concentration lower than the harmonic concentration of tri-n-butyl-n-pentylammonium bromide. The melting start temperature of the hydrate below this harmonic concentration was 4 ° C. and the melting end temperature was 6 ° C. The amount of latent heat at the time of melting was 144 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.8 J / g · K. Although the amount of latent heat is smaller than that of a harmonic hydrate, it can be used as a main component of a cold-retaining agent that can be kept cold in the range of 4 to 6 ° C.

3) Main component example 3: Tri-n-butyl n-pentylammonium chloride (TBPACl) harmonic concentration hydrate The tri-n-butyl n-pentylammonium chloride hydrate of main component example 3 has its harmonic melting point (harmonic) as shown in Table 1. Concentration 33%) is 9 ° C, the latent heat at the harmonic melting point is 195 J / g, the specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K, tri-n-butyl-n-pentylammonium bromide water It can be used as a main component of a cryogen having a latent heat equivalent to that of a Japanese product.

4) Main component examples 4, 5, and 6: Mixed hydrate of tri-n-butyl-n-pentylammonium bromide (TBPAB) and tetra-n-butylammonium bromide (TBAB) Harmony of tri-n-butyl-n-pentylammonium bromide (TBPAB) Concentration hydrates and harmonic concentration hydrates of tetra-n-butylammonium bromide (TBAB) in a weight ratio of 50:50 (main component example 4), 30:70 (main component example 5), 20:80 ( The characteristics of the mixed hydrate mixed at the ratio of the main component example 6) were examined.

As shown in Table 1, these three types of hydrates have a melting temperature of 8 to 9.5 ° C, a latent heat of 182 to 186 J / g, and a specific heat of the aqueous solution in which the hydrate has melted is 3.6 to 3 It is 0.7 J / g · K, and can be used as a cryogen that can be kept cold in the range of 8 to 9.5 ° C.
Further, as can be seen from Table 1, in the main component examples 4 to 6, the melting temperatures are changed to 8 ° C., 9 ° C., and 9.5 ° C., respectively. From this, by changing the weight ratio between the tri-n-butyl-n-pentylammonium bromide (TBPAB) harmonic hydrate and the tetra-n-butylammonium bromide (TBAB) harmonic hydrate, the desired temperature can be changed. It was confirmed that a mixed hydrate having a melting temperature in the range could be obtained, and the cold keeping temperature of the cryogen could be adjusted.

From the above, as a method for setting the melting point of the cryogen, the cryogen is mainly composed of tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate. It is conceivable that the blending ratio of n-butyl-n-pentylammonium hydrate and tetra-n-butylammonium bromide hydrate is determined in the range of 1 to 95% by weight.
Each hydrate is preferably a harmonic hydrate. This is because the amount of latent heat can be maximized to keep cold.

  Since the cold insulation performance test was done about said main component examples 1 and 4, the result is demonstrated. In the cold insulation performance test, the cold insulation material in which 3 kg of paraffin (n-tetradecane) was filled in a polyethylene bag as a comparative example was cooled to 0 ° C. and solidified, and the cold insulation material was used as a vacuum insulation panel. It was mounted on the bottom of a cold storage box having a capacity of 20 liters, the cold storage box was placed in a constant temperature room at 30 ° C., and the temperature change inside the cold storage box was measured.

1 and 2 are graphs showing the results of a cold insulation performance test. FIG. 1 shows main component examples 1 and 2, and FIG. 2 shows a comparative example. In each figure, the vertical axis represents temperature (° C.) and the horizontal axis represents elapsed days (days).
As can be seen from FIG. 1, in the main component example 1, the temperature inside the cold insulation box remained constant at 6 ° C., and the melting of the cold insulation material was completed after 3.5 days and the temperature rose.
Moreover, in the main component example 4, the temperature inside the cool box remained constant at 8 ° C., and the melting of the cool material was completed after 3.5 days and the temperature rose.
On the other hand, in the comparative example, the temperature inside the cold insulation box remained constant at 6 ° C., and after 2.7 days had elapsed, melting of the cold insulation material was completed and the temperature rose rapidly.
From the above, it can be seen that the main component examples 1 and 4 are suitable as the main component of the cryogen because the cool time is longer and the temperature rise after melting is smaller than the comparative example.

  Next, the characteristics of the cryopreservation example in which the gelling agent is added to the main component composed of the hydrate are shown in Table 2 below, and each example will be described based on Table 2.

1) Example 1
In Example 1, a cold-retaining agent in which 1 wt% of sodium stearate was added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide (TBPAB) in a concentrated concentration (34 wt%) with respect to the aqueous solution, and sodium stearate was not added as Comparative Example 1. The characteristics of TBPAB aqueous solution with the same concentration were investigated.
When sodium stearate is added to and mixed with an aqueous TBPAB solution, the aqueous solution temperature is raised to about 50 ° C. to promote dissolution. When it reaches room temperature after being dissolved, the viscosity of the aqueous solution becomes remarkably large, resulting in a gel-like product having no fluidity.

The thermal conductivities of Example 1 and Comparative Example 1 were measured by a hot wire method (probe method). That is, the amount of heat released per unit time of the unit length of the heater wire is Q (W / m), and the rise Δθ of the surface temperature of the heater wire from time t ₁ (s) to time t ₂ (s) is measured. The thermal conductivity λ was determined by the following formula.

  Moreover, the supercooling release performance was evaluated by the following method. 5 g of the sample was sealed in a 10 ml glass test tube, and the glass test tube in which the sample was sealed was immersed in a 15 ° C. hot bath and then immersed in a −5 ° C. cold bath. The ratio of the portion crystallized after elapse of a predetermined time after immersion in a cooling bath was measured, and the case where 1/2 or more of the entire sample was crystallized was evaluated as ○, and less than 1/2 was evaluated as x.

  As shown in Table 2, it was confirmed that Example 1 not only became a gel-like product but lost fluidity, but also had a thermal conductivity approximately twice that of Comparative Example 1 and could efficiently store cold. In addition, in Comparative Example 1, the overcooling release performance was 1/20 of the entire crystallized portion while immersed in the cooling bath for 1 hour, whereas in Example 1, it was immersed in the cooling bath for 1 hour. It was confirmed that supercooling can be easily released by 2/3 of the total crystallized portion.

2) Example 2
Example 2 was compared with a cooling agent obtained by adding 1 wt% of calcium palmitate to an aqueous solution of 17 wt% tri-n-butyl n-pentyl ammonium bromide (TBPAB) and 20 wt% tetra-n-butyl ammonium bromide (TBAB). As Example 2, the characteristics of an aqueous solution of TBPAB and TBAB having the same concentration without adding calcium palmitate were examined.
When calcium palmitate is added to and mixed with an aqueous solution of TBPAB and TBAB, the viscosity of the aqueous solution becomes remarkably large, and a gel-like product having no fluidity is obtained.
As shown in Table 2, it was confirmed that Example 2 not only became a gel-like product but lost fluidity, but also had a thermal conductivity approximately twice that of Comparative Example 2 and could efficiently store cold. Moreover, the supercooling release performance was 1/3 of the entire crystallized portion while being immersed in the cooling bath for 30 minutes in Comparative Example 2, whereas in Example 1, it was while being immersed in the cooling bath for 30 minutes. It was confirmed that the amount of crystallized portion was almost the entire amount, and the supercooling could be easily released.

  In the above examples, the properties were evaluated using sodium stearate and calcium palmitate as the gelling agent, but the same effect can be obtained by using the other gelling agents described above. A plurality of gelling agents may be used in combination.

  In addition to the gelling agent, the cold-retaining performance is reduced in addition to the gel-retaining agent composed mainly of an aqueous solution containing tri-n-butyl-n-pentylammonium bromide or tri-n-butyl-n-pentylammonium chloride. It can be added within the range not to be.

  In addition, the said cold insulating agent can also be used as a cooling inhibitor. In other words, when the ambient environment is cooler than the object to be stored, a cooling material filled with a cryogen that is melted around the object to be stored is placed in the container, and when a hydrate is generated from the aqueous solution and solidifies. It absorbs the cold from the surrounding environment to prevent the object to be stored from cooling. Used to prevent fresh vegetables and foods from freezing in winter and store at an appropriate temperature.

It is a graph which shows the result of the cold insulation performance test of the cryogen main component which concerns on embodiment of this invention. It is a graph which shows the result of the cold insulation performance test of a comparative example.

Claims (11)

A cryogen comprising a tri-n-butylalkylammonium salt, water, and a gelling agent. A cryogen comprising tri-n-butyl-n-pentylammonium bromide, water and a gelling agent. A cryogenic agent comprising tri-n-butyl-n-pentylammonium bromide hydrate as a main component and containing a gelling agent. A cryoprotectant comprising tri-n-butyl-n-pentylammonium chloride, water and a gelling agent. A cryogenic agent comprising tri-n-butyl-n-pentylammonium chloride as a main component and containing a gelling agent. A cryogen comprising a tri-n-butylalkylammonium salt, a tetraalkylammonium salt, water and a gelling agent. A cooling agent comprising tri-n-butyl-n-pentylammonium bromide, tetra-n-butylammonium bromide, water and a gelling agent. A cold-retaining agent comprising tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate as a main component and containing a gelling agent. A cooling agent comprising tri-n-butyl-n-pentylammonium chloride, tetra-n-butylammonium bromide, water and a gelling agent. A cold-retaining agent comprising tri-n-butyl-n-pentylammonium chloride hydrate and tetra-n-butylammonium bromide hydrate as a main component and containing a gelling agent. A cold insulating material comprising the container or a bag filled with the cold insulating agent according to any one of claims 1 to 10.

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